1. Field of the Invention
The present invention relates to an assist air control apparatus for a fuel injection valve particularly for an internal combustion engine.
2. Description of the Related Art
There is conventionally available, an air assist control apparatus serving also as an idle speed control (ISC) apparatus, as disclosed in Japanese Patent Unexamined Publication No. 58-195,057. According to the disclosure, the apparatus supplies assist air to a fuel injection device by opening and closing a flow control valve, and also supplies air for ISC.
In this conventional control method, however, when a high air flow quantity in idling is required at low temperatures, as opening/closing time interval of the control valve becomes short, it is impossible for the control valve to follow the requirements and thus the controllability of the ISC functions may be deteriorated. In addition, the pulsating noise caused by the intake pulses upon opening or closing the control valve is of a frequency different from that of the pulsating noise caused after warming-up, and special measures against it are necessary.